ECM woes again

[Haggar]

Gipper,

 

I hope you find it.  I am pretty sure they can tell too much amperage flowed through pin 37.  Here is the wiring diagram for an 01.  That wire goes through three junctions and goes near the steering column. so good potential for issues.  It is a computer output going to a driver, so it should only see a small amount of amperage flow.

 

Disconnect the ECM and pull the cluster and check to see if you have continuity to ground on the orange/black wire.  If you do, its in the wiring.  It will be harder to troubleshoot the cluster itself.  hope that it is in the wiring.

 

GL

 

Hag

2001 FSM Ram 8w-30-34.pdf

[Mopar1973Man]

Pin 37 is the Wait To Start light.

 

[gipperkid]

22 hours ago, pepsi71ocean said:

 

We'll I'd pull the instrument cluster and then check the wiring between the cluster and the ECM. Then I'd look at the cranking voltage and see what it gets down to when cranking. I'd pull the vp44 relay in the box and crank it over. 

 

I'd wonder about that. Either could be an issue, but so could be ac blow by from there alternator or the grounds being dirty better the cluster and the passenger side battery where the ECM ground is. 

 

So just put the DVM on the battery posts while cranking?

 

I did the W-T ground mod and have .016 at the alternator.

 

I didn't do anything with the passenger battery grounds.

 

14 hours ago, Haggar said:

Gipper,

 

I hope you find it.  I am pretty sure they can tell too much amperage flowed through pin 37.  Here is the wiring diagram for an 01.  That wire goes through three junctions and goes near the steering column. so good potential for issues.  It is a computer output going to a driver, so it should only see a small amount of amperage flow.

 

Disconnect the ECM and pull the cluster and check to see if you have continuity to ground on the orange/black wire.  If you do, its in the wiring.  It will be harder to troubleshoot the cluster itself.  hope that it is in the wiring.

 

GL

 

Hag

2001 FSM Ram 8w-30-34.pdf 232.87 kB · 1 download

 

So test continuity at the plug going to the cluster? Or test between the ECM plug and cluster plug?

 

I have looked at the wiring diagram, but where does the wire for pin 37 begin/terminate.

[dripley]

8 hours ago, gipperkid said:

I did the W-T ground mod and have .016 at the alternator.

 

I didn't do anything with the passenger battery grounds

Part of that ground mod was to relocate the ECM and VP ground from the passanger battery. Thats the ground @pepsi71ocean is speaking of.

[pepsi71ocean]

10 hours ago, gipperkid said:

 

So just put the DVM on the battery posts while cranking?

 

I did the W-T ground mod and have .016 at the alternator.

 

I didn't do anything with the passenger battery grounds.

 

 

So test continuity at the plug going to the cluster? Or test between the ECM plug and cluster plug?

 

I have looked at the wiring diagram, but where does the wire for pin 37 begin/terminate.

 

Correct, you want to check both the cranking voltage and do a vdrop test on it to confirm that the cables aren't going bad.

[gipperkid]

12 hours ago, dripley said:

Part of that ground mod was to relocate the ECM and VP ground from the passanger battery. Thats the ground @pepsi71ocean is speaking of.

 

Well I did remove the grounds from the wire loom and relocated those grounds to the case next to the VP.

[dripley]

30 minutes ago, gipperkid said:

 

Well I did remove the grounds from the wire loom and relocated those grounds to the case next to the VP.

That was good thing getting the grounds, charge wire and signal out of the same wiring harness. That really cut my AC ripple down alot. I went from .035 to .010 just with the mod on a 6 year old AZ alternator.

[Haggar]

Gip,

 

Sorry, was out of town yesterday.   In the FSM page I attached you will see the OR/BK (Orange with black tracer)  wire goes from pin 37 on the ECM connector to pin 8 on the C1 connector at the cluster.

 

You can look up each of those connectors in the 8w-80 section of the manual for "connector pin-outs" and the 8w-90 section for "connector locations"  (the 8w-90 section will also help you find the connectors C134, C130 and C126.)

 

If you are trying to "check for shorts" and you are not using the FSM wiring diagrams, you may not be finding all the possible areas that a short can be and causing problems.

 

GL HTH
 

Hag